Electromechanical parking brakes having an electric brake motor which presses a brake piston with its brake lining against a brake disk to generate a clamping force which holds the vehicle at a standstill. Such a parking brake is discussed in DE 103 61 042 B3, for example.
The brake disk is usually also acted upon by the hydraulic vehicle brake. In the case of intensive brake usage, the brake disk may reach high temperatures and may expand due to the heat. If the parking brake is operated in this state, the clamping force may decrease during the cooling down of the brake disk.